99% of the time mulch is a temporary condition. Because it decomposes and washes, it needs to be added to periodically. As it disintegrates, weeds begin to move in. It's better if intentional plants do the job of covering ground. I can't imagine mulch lasting 5 years on this slope. (Maybe a mulch blanket that is pinned to earth ...?) Were this mine, I would not want a row of pine trees at top and a mixture of shrubs/grasses on the remainder. To cover the whole bank with small, flowering trees/large shrubs could be done with a triple staggered row and would only require about 20 plants for that part of the planting. The in-between space could be hydroseeded with grass/wildflowers. Another tree/shrub that comes to mind as a good solution for this bank is Sumac. It's pretty, does not get to towering proportions, has beautiful fall color and forms groves so would easily establish its own "forest." Redbud Staghorn Sumac

is this an actual flowing river.. or stream .... is it really necessary to opt for a water loving tree.. is what i am wondering ... planting on a hill is the only limiting factor in most circumstances ... as the trees will put their roots where they want them.. as compared to going the rest of the way downhill and putting their feet in the water ... those horrible cottonwoods/poplars like to be near water ... i wonder if your county has a soil conservation office????? as in theory.. that is what your goal is .... they would be more in tune as to what trees would favor your county ... ken

The shrubs growing on the slope look that they have been there quite a while and seem to be growing straight up. (Sometimes, if there is a bend like an old-fashioned walking stick handle in the stem near to the ground, that bend can indicate that the land is slumping.) About the tree roots showing: there's not a great deal of topsoil from what I could see so the roots have probably spread out to forage for food and water. A number of tree species have suface roots - some quite gnarled and obvious. Think swamp cypress for a start. Unless the trees are very tall and your local prevailing winds are fierce or unpredictable you aren't likely to get windthrow. On a slope such as yours I'd be looking for grooves cut by runoff from the top as the precursor to shallow gullying - and that didn't seem to be happening. Personally, I wouldn't spend on 'posh plants' for such a slope. I'd ask for 'pioneer-type' shrubs - preferably native to your area. If you have a native plants nursery near you - pick their brains. Grasses, creepers, low-nutrient environment shrubs and sub-shrubs. That soil is obviously not rich - it hasn't been colonised by much at all. If you need clues and there are cuttings at the sides of your roads check there for what will establish and thrive and stay seemly. (No one needs a slope covered in fire risk weeds!) When you visit with the plant place/s ask for SPECIFIC guidance on how to plant up a steep slope. If it has a high clay content - let them know because it will change what they will advise. If there is any better soil available on your lot, and you can spare some - mix it in with the slope soil when planting but don't bother putting in fine compost. All that happens is the plants grow out to the limits of the top grade environment and then either sulk or die. Think about buying your reveg plants in 'root trainer' tubes rather than big cans or baggies. They'll be younger and better equipped to strike out, rootwise. Hear you when you say you're budget-constrained. See if you can legally collect native seedlings of suitable plants, grow them on, then plant out. Sometimes a neighbour can be a good source. Under the bird feeder, in a garden, can be another - but expect a lot of berry-producing plants ;-) And, as the slope is a bit of a challenge - could you devise a ladder to get you upslope for planting? Or a scaffoldiong arrangement. Something with wide enough treads so you don't end up with anguished feet!

Part of my streambank is like yours; almost vertical. I'm assuming the stream can rise during rains. Xanthorrhiza simplicissima and Leucothoe are good, low-growing (native)colonial shrubs which will stabilize the bank. Vinca minor and V. major should also work, as might Lamium. Chrysogonum virginianum 'Eco Lacquered Sunset'and Ajuga spread vigorously in shade. A few of the low-growing bamboos will spread slowly in deep shade, but beware of their aggressiveness if they find a brighter area. Plants competing with tree roots will need supplemental water for a few years until established. That means watering several hours a week with an oscillating sprinkler. I think adding soil or making terraces would be a waste. Lessening the tree cover would certainly help your ground covering plants grow.